Page:The Annual Register 1899.djvu/534

 110 SCIENCE. [1899.

light are accepted by the reason only as a logical necessity ; and music and art are illusions.

In order to trace the mode of restoration of function after neural section, the distal segment of a divided sciatic nerve was attached to the central segment in a half-rotated position. As the fibres in the two segments no longer corresponded, a functional recovery necessitated the genesis of new paths for the interrupted nerve current. Neverthe- less Dr. Kennedy found that co-ordinated movements began on the seventh day and were perfected from the fourteenth to the twenty- first day after the operation. A subsequent examination of the distal segment revealed the presence of Wallerian degeneration, and of a complete renewal of young nerve-fibres. This rapidity of resumption was not exceeded in control cases in which the two portions of a divided sciatic nerve were united in their normal attitude. Hence it would seem that early restoration of function after nerve section is due, not to " healing by the first intention " but to a reproduction of neural elements in the peripheral segment.

It is confirmed by Messrs. Hopkins and Hope that during the period of increased nitrogen -excretion that follows a meal, the rise in uric acid occurs sooner and has a shorter duration than the rise in urea. They regard this as evidence that the acid does not originate from the nuclein of the diet on which the early stages of digestion have little effect, but is due to a synthetic process set up by some other and more soluble constituent of food.

The quotient C/N in the normal urine of men and dogs is greater than in urea. The urine must, therefore, as Herr Pregl points out, contain something that is poorer than urea in nitrogen ; and this he thinks to be hydroxy pro teic acid.

Mr. Weld, having pursued the question whether ordinary sound- vibrations can be perceived by ants, finds that these creatures are greatly excited when, enclosed in a test tube, they are brought near a milled disc rotating rapidly. When the same shrill sounds were pro- duced close to a colony protected by glass the ants displayed the utmost alarm. As great proximity of the vibrating body was a prominent factor in these experiments, it would seem likely that what the ants perceived had not a really acoustic quality.

The hexagonal arrangement of the cells of bees, is due, Professor Dawson believes, not to a structural instinct of those insects, but to a kind of crystalline formation consequent on the cooling of the wax.

Biology.

Dr. Wilson, in tracing the development of the lung in ceratodus finds that it arises, as with amphibians and higher animals, in a mid-ventral pharyngeal gut immediately posterior to the gill region. This expands into an unpaired vesicle which ultimately shifts its position until it lies dorsally.

Mr. Kerr rejects the two hypotheses that are used to explain the origin of the paired limbs. He does not think that they are derived either from a once continuous lateral fin-fold, or from the septa between